LEDs (Light Emitting Diode) or light bulbs are generally used as the light sources of automotive lamps. Recently, there has been an effort to use laser diodes for the automotive light sources, but an efficient technology has not been proposed up to now.
Presently, laser diodes are generally used in the medical and industrial fields. The laser diode (LD), a general term of lightwave oscillators and amplifiers using stimulated emission of photons by optical transition of electrons in semiconductors, has two electrodes. The laser diodes have the advantages that they are small in size and light in various lasers and can be manufactured in large quantities at low costs through semiconductor processes.
However, the laser diodes that are under development now for automotive lamp modules have a problem in that they are difficult to use for vehicles, because the structures are complicated and the heat sinks for heat dissipation are large in size. In particular, the existing substrates mounted with laser diodes have configurations having difficulty in effective heat dissipation, because the other regions except for the circuit patterns are in insulation.